The present invention relates to a vehicle body acceleration sensor for use with a seat belt, and more particularly, to an improvement in a vehicle body acceleration sensor for use with a seat belt which is used for a seat belt retractor attached to a backrest of a reclining seat of a vehicle and which activates lock means for preventing withdrawal of a webbing in the event of an emergency.
For a seat belt apparatus for safely retaining a vehicle occupant on his seat, there has conventionally been used an emergency lock type retractor which has an emergency lock mechanism for physically locking a retractor through use of inertia sensing means for responding to urgent acceleration, collision, or deceleration and which safely and effectively restrains the occupant.
Inertia sensing means used for such an emergency lock type retractor includes a vehicle body acceleration sensor for sensing the acceleration of the vehicle body. For example, the vehicle body acceleration sensor is constructed such that, when an inertial body is moved as a result of collision or inclination of the vehicle body, a sensor arm provided on top of the inertial body is pivoted, thereby activating lock means for locking rotation in the direction in which the webbing is drawn-out from a take-up shaft around which a webbing is wound.
Recently, there have been proposed various types of vehicle body sensors for use with a seat belt, in which a retractor such as that mentioned previously is provided within a backrest of a reclining seat and which, even when the backrest is titled, can be activated in the same way as when the backrest is not reclined.
For example, like vehicle body acceleration sensors described in German Patent Publication No. 4,032,157, U.S. Pat. No. 4,978,087, and Japanese Patent Unexamined Publications No. Hei.1-202553 and No. Hei.3-148350, there have already been proposed various types of vehicle body acceleration sensors which are provided with transmission means, such as a flexible shaft or a gear device, for controlling the angle of a sensor case by pivotal movement of the sensor case about its pivot in synchronization with reclining action of a backrest, in such a way that an inertial body support surface formed on the sensor case is retained in an appropriate position with respect to the sensor case pivotally supported by a retractor base regardless of reclining angle of the backrest, or are provided with rotary drive means such as a servo motor which rotatively actuates the sensor case according to a reclining angle of the backrest.
By means of the seat belt apparatus having such a structure, even when the backrest is inclined or slid between the full forward and full back positions, the positional relationship between a shoulder belt of the webbing and a backrest remains unchanged, thereby ensuring superior restraining performance.
In a case where the sensor case is rotatively actuated by means of a servo motor, or the like, according to the reclining angle of the backrest, use of a motor adds to component costs, results in an increase in the number of components, and renders the structure of the seat belt apparatus complicated, thus leading to an increase in manufacturing costs.
In a case where the sensor case is rotated, through use of the transmission means, about its pivot in synchronization with the reclining action of the backrest according to the reclining angle of the backrest, the pivotable range of the sensor case is set so as to correspond to an optimum working range of the retractor which is attached to the backrest and is capable of appropriately restraining the occupant by means of webbing. However, the optimum working range of the retractor generally constitutes a portion of the reclining range of the backrest and is narrower than the reclining range. For this reason, in a case where the sensor case is rotatively actuated by means of transmission meansxe2x80x94such as a flexible shaft or a gear devicexe2x80x94interposed between the sensor case and seat hardware, when the backrest is reclined beyond the optimum working range of the retractor, the sensor case is actuated by way of the transmission means, thereby resulting in interference with another component or straining and damaging the sensor case.
To prevent such a problem, the angle at which the backrest is reclined is limited so as to match the pivotable range of the sensor case, with the result that the range of inclination of the backrest becomes narrower than that of a seat having not a built-in retractor, thereby rendering a vehicle seat very difficult to use.
In contrast, in a case where the sensor case is arranged so as to be able to pivot in synchronization with the reclining action of the backrest even when the backrest in reclined beyond the optimum working range of the seat belt, a large space is required for movement of the sensor case, thereby rendering the retractor large.
An angle sensing means provided in the transmission means for sensing the inclination of the backrest includes an angle sensing means for sensing the inclination of the backrest by sensing relative rotation between a member disposed in a seat and a member which is provided on the side of a recliner mechanism (a hinge mechanism of the seat) facing the backrest and which pivots together with the backrest.
Since the angle sensing means pivots in agreement with the pivotal movement of the backrest, the pivot of the angle sensing means is desirably placed in line with the reclining pivot of the backrest. As shown in FIG. 78, if a reclining pivot O of the backrest does not match a pivot Q of the angle sensing means, a pivotable angle xcex8 of the backrest does not match a pivotable angle xcex1 of the angle sensing means at, e.g., a point V (a position where the angle sensing means is mounted on the backrest), thereby rendering impossible correct adjustment of the orientation of the sensor case.
In order to cause the reclining pivot of the backrest to coincide with the pivot of the angle sensing means, the reclining mechanism on which the angle sensing means is mounted and the angle sensing means must be manufactured with a high degree of dimensional precision. Both the reclining mechanism and the angle sensing means require a large number of components, thereby becoming expensive.
Accordingly, the object of the present invention is to provide a vehicle body acceleration sensor to be disposed in a retractor mounted on a backrest, and more particularly, to provided a vehicle body acceleration sensor for use with a seat belt which is capable of reliably and stably sensing the acceleration of a vehicle body regardless of the reclining angle of the backrest and which enables a reduction in manufacturing costs by employment of a simple mechanism.
The foregoing object of the present invention is achieved by a vehicle body acceleration sensor for use with a seat belt comprising:
a sensor case which is supported in a movable manner by a retractor base mounted on a backrest of a reclining vehicle seat;
a sensor arm which is pivotally mounted on the sensor case or the retractor base so as to move lock means between a first position where the lock means is actuated and a second position where the lock means becomes inoperative, the lock means preventing a take-up shaft, around which a webbing is wound, from rotating in a direction in which the webbing is drawn-out;
an inertial body which moves in relation to an inertial body support surface of the sensor case upon receipt of a velocity change of greater than a predetermined value, thereby moving the sensor arm to the first position; and
transmission means for moving the sensor case in synchronization with reclining action of the backrest according to a reclining angle of the backrest so that the inertial body support member is held at an appropriate orientation regardless of reclining angle of the backrest, wherein the lock means is actuated by means of movement of the inertial body caused when a predetermined acceleration acts on the vehicle body.
By means of the foregoing structure of the sensor case, when the inclination of the backrest is changed, the inertial body support surface is held at an appropriate position by means of transmission means which is actuated in synchronization with reclining action of the backrest. The vehicle body acceleration sensor can properly operate even when the backrest is in another reclined position and can sense the acceleration of the vehicle body without fail.
The object of the present invention is also achieved by a vehicle body acceleration sensor for use with a seat belt including:
a sensor case which is supported in a movable manner by a retractor base mounted on a backrest of a reclining vehicle seat;
a sensor arm which is pivotally mounted on the sensor case or the retractor base so as to move lock means between a first position where the lock means is actuated and a second position where the lock means becomes inoperative, the lock means preventing a take-up shaft, around which a webbing is wound, from rotating in a direction in which the webbing is drawn-out;
an inertial body which moves in relation to an inertial body support surface of the sensor case upon receipt of a velocity change of greater than a predetermined value, thereby moving the sensor arm to the first position; and
transmission means for moving the sensor case in synchronization with reclining action of the backrest according to a reclining angle of the backrest so that the inertial body support member is held in an appropriate orientation regardless of reclining angle of the backrest, wherein the lock means is actuated by means of movement of the inertial body caused when a predetermined acceleration acts on the vehicle body, the vehicle body acceleration sensor being characterized by that
the transmission means includes a synchronous movement cancelation mechanism capable of canceling the movement of the sensor case which is in synchronization with the reclining action of the backrest.
By means of the foregoing structure of the sensor case, when the inclination of the backrest is changed, the inertial body support surface is held at an appropriate position by means of transmission means which is actuated in synchronization with reclining action of the backrest. The vehicle body acceleration sensor can properly operate even when the backrest is in another reclined position and can sense the acceleration of the vehicle body without fail.
When the backrest is reclined beyond the optimum working range of the seat belt, the synchronous movement cancelation mechanism can cancel the pivotal movement of the sensor case in synchronization with the reclining action of the backrest. Therefore, the reclining angle of the backrest is prevented from being limited by the pivotable range of the sensor case. Further, the sensor case is prevented from being unnecessarily rotated in synchronization with the reclining action of the backrest, thereby preventing the retractor from becoming bulky.
In this case, the pivotable range of the sensor case is set so as to become slightly larger than the reclining range of the backrest within the optimum working range of the seat belt, so as to prevent damage to the sensor case.
More preferably, the transmission means comprises
a slide member movably disposed in a seat portion of the reclining seat;
a cam plate which causes the slide member to advance or recede within only the pivotable range of the sensor case according to the reclining angle of the backrest; and
a flexible transmission member, one end of which is connected to the slide member and the other end of which is connected to the sensor case and which transmits the movement of the slide member to the sensor case. As a result, the transmission member that retains the inertial body support surface in an optimal state in synchronization with the reclining action of the backrest is made up of a simple mechanism comprising the slide member, the cam plate, and the flexible transmission member and does not require an expensive component such as a motor. Therefore, a rise in manufacturing costs can be prevented.
More preferably, the transmission member comprises
a transmission member which is actuated in synchronization with the reclining action of the backrest; and
a synchronous movement cancelation mechanism which is interposed at least between a retractor-side joint section of the transmission section and the sensor case and which prevents the sensor case from moving in synchronization with the reclining action of the backrest when the backrest is reclined beyond the optimum working range of the seat belt. There can be prevented complication of a mechanism which is provided on the seat reclining pivot of the backrest and which transmits the reclining action of the backrest to a seat-reclining-pivot-side joint section of the transmission member to thereby actuate the sensor case. Consequently, the vehicle body acceleration sensor can cope with a plurality of types of seats by merely minor modification of the retractor.
More preferably, the synchronous movement cancelation mechanism comprises a slider which is joined to the sensor case by means of the retractor-side end section of the transmission member and has a range of movement limited to the pivotable range of the sensor case that is set to the optimum working range of the set belt; and an elastic member which is interposed between the slider and the retractor-side joint section of the transmission member and which is resiliently deformable in the direction of movement of the slider upon receipt of a load of greater than a predetermined value. When the backrest is reclined beyond the optimum working range of the seat belt, the elastic member deflects and absorbs the displacement of the transmission member, thereby readily preventing the sensor case from pivoting in synchronization with the reclining action of the backrest.
More preferably, the synchronous movement cancelation mechanism comprises a gear with a cam which engages with the retractor-side joint of the transmission section and is rotated; and the sensor case which follows the cam of the gear and pivots within a pivotable range which is set so as to correspond to the optimum working range of the seat belt. When the backrest is reclined beyond the optimum working range of the seat belt, the sensor case can be readily prevented from pivoting in synchronization with the backrest.
The object of the present invention is also achieved by a vehicle body acceleration sensor for use with a seat belt including:
a sensor case which is movably supported by a retractor base mounted on a backrest of a reclining vehicle seat;
a sensor arm which is pivotally mounted on the sensor case or the retractor base so as to move lock means between a first position where the lock means is actuated and a second position where the lock means becomes inoperative, the lock means preventing a take-up shaft, around which a webbing is wound, from rotating in a direction in which the webbing is drawn-out;
an inertial body which moves in relation to an inertial body support surface of the sensor case upon receipt of a velocity change of greater than a predetermined value, thereby moving the sensor arm to the first position; and
transmission means for moving the sensor case in synchronization with reclining action of the backrest according to a reclining angle of the backrest so that the inertial body support member is held in an appropriate orientation regardless of reclining angle of the backrest, wherein the lock means is actuated by means of movement of the inertial body caused when a predetermined acceleration acts on the vehicle body, the vehicle body acceleration sensor being characterized by
the transmission means including a cam plate whose cam surface extends in the circumferential direction from the seat reclining pivot of the backrest, and a transmission member which follows the cam surface of the cam plate and pivots the sensor case in conjunction with the reclining action of the backrest.
By means of the foregoing structure of the sensor case, when the inclination of the backrest is changed, the transmission member follows the cam surface to thereby pivot the sensor case in synchronization with the reclining action of the backrest. Accordingly, the inertial body support surface is retained in an appropriate orientation. The vehicle body acceleration sensor can properly operate regardless of the reclined angle of the backrest and can sense the acceleration of the vehicle body without fail.
The transmission member is made up of a simple mechanism comprising a transmission member such as a rod member having a simple shape or a flexible transmission member and a cam plate, both of which can be readily and inexpensively mass-produced by press-working of plate material, and does not require an expensive component such as a motor. Therefore, a rise in manufacturing costs can be prevented.
By provision of cam plates having different cam profiles, there may be produced a vehicle body acceleration sensor of superior versatility which can be used with a plurality of types of reclining seats and seat belt retractors through selection of an appropriate one of the cam plates.
More preferably, the cam surface of the cam plate comprises a synchronous movement area in which the sensor case is pivoted in synchronization with the reclining action of the backrest within only the optimum working range of the seat belt, and non-synchronous movement areas in which the sensor case is not pivoted in synchronization with the reclining action of the backrest. When the backrest is reclined within the optimum working range of the seat belt, the transmission member follows the synchronous movement area of the cam surface and causes the sensor case to pivot in synchronization with the reclining action of the backrest. In contrast, when the backrest is reclined beyond the optimum working range of the seat belt, the transmission member follows a non-synchronous movement area of the cam surface and prevents the sensor case from pivoting in synchronization with the reclining action of the backrest. Accordingly, the range of reclining angle of the backrest is not limited by the pivotable range of the sensor case. Further, the sensor case is not required to pivot more than necessary so as to stay in synchronization with the reclining action of the backrest, thereby preventing the retractor from becoming bulky.
Here, the pivotable range of the sensor case is set so as to become slightly wider than the range of reclining angle of the backrest within the optimum working range of the seat belt so as to prevent damage to the sensor case.
More preferably, a cam contact section formed on the cam-plate-side end section of the transmission member which moves back and forth toward the cam surface of the cam plate is set so as to move back and forth in such a direction as to impart an optimum pressing force on the entire surface of the cam surface with which the cam contact section makes slidable contact. Consequently, the cam-plate-side end section of the transmission member can be prevented from being twisted and protected from excessive force.
More preferably, the cam plate is fixed on a seat portion of the reclining seat, and the cam-plate-side end section of the transmission member is fixed on the backrest so as to be able to move back and forth toward the cam surface of the cam plate. As a result, the transmission member is prevented from being bent every time the backrest is reclined, thereby preventing deterioration of durability of the transmission member.
More preferably, the transmission means comprises a cam plate which has an inner peripheral cam surface and extends in the circumferential direction of the seat reclining pivot of the backrest; a follower which is provided on the inner peripheral cam surface of the cam plate so as to be able to move back and forth; and a transmission member which has a cam-plate-side end section joined to the follower and a retractor-side section joined to the sensor case and which transmits the forward and backward movement of the follower to the sensor case. When the backrest is reclined, the follower that follows the inner peripheral cam surface pivots the sensor case in synchronization with the reclining action of the backrest by way of the transmission member, thereby retaining the inertial body support surface in an appropriate orientation. As a result, regardless of the reclining angle of the backrest, the vehicle body acceleration sensor can operate appropriately and can sense the acceleration of the vehicle body without fail.
The transmission member is made up of a simple mechanism comprising a transmission member such as a rod member having a simple shape or a follower and a cam plate which can be readily and inexpensively mass-produced by press-working of plate material, and does not require an expensive component such as a motor. Therefore, a rise in manufacturing costs can be prevented.
By provision of cam plates having different inner peripheral cam surfaces, there may be produced a vehicle body acceleration sensor of superior versatility which can be used with a plurality of types of reclining seats and seat belt retractors through selection of an appropriate one of the cam plates.
More preferably, the inner peripheral cam surface of the cam plate is provided with only the synchronous movement area in which the sensor case is pivoted in synchronization with the reclining action of the backrest within only the optimum working range of the seat belt. Alternatively, the inner peripheral cam surface is provided with a synchronous movement area in which the sensor case is pivoted in synchronization with the reclining action of the backrest within only the optimum working range of the seat belt, and non-synchronous movement areas in which the sensor case is prevented from pivoting in synchronization with the reclining action of the backrest. As a result, when the backrest is reclined beyond the optimum working range of the seat belt, the follower is disengaged from the inner peripheral cam surface or follows a non-synchronous movement area of the inner peripheral cam surface, so that the sensor case is prevented from pivoting in synchronization with the reclining action of the backrest. Accordingly, the reclining angle of the backrest is not limited by the pivotable range of the sensor case. Further, the sensor case is not required to pivot more than necessary in synchronization with the reclining action of the backrest, thereby preventing the retractor from becoming bulky.
Here, the pivotable range of the sensor case is set so as to become slightly wider than the range of reclining angle of the backrest within the optimum working range of the seat belt so as to prevent damage to the sensor case.
More preferably, the follower has a roller which moves over the inner peripheral cam surface in a rotatable manner, and hence frictional resistance between the inner peripheral cam surface and the follower can be reduced, thereby enabling smooth forward and backward movement of the follower.
More preferably, the cam plate is mounted on the seat portion of the reclining seat, and the follower is fixed on the backrest so as to be able to move back and forth along the inner peripheral cam surface of the cam plate. Therefore, the transmission member is prevented from being bent every time the backrest is reclined, thereby preventing deterioration of durability of the transmission member.
The object of the present invention is also achieved by a vehicle body acceleration sensor for use with a seat belt including:
a sensor case which is movably supported by a retractor base mounted on a backrest of a reclining vehicle seat;
a sensor arm which is pivotally mounted on the sensor case or the retractor base so as to move lock means between a first position where the lock means is actuated and a second position where the lock means becomes inoperative, the lock means preventing a take-up shaft, around which a webbing is wound, from rotating in a direction in which the webbing is drawn-out;
an inertial body which moves in relation to an inertial body support surface of the sensor case upon receipt of a velocity change of greater than a predetermined value, thereby moving the sensor arm to the first position; and
transmission means for moving the sensor case in synchronization with reclining action of the backrest according to a reclining angle of the backrest so that the inertial body support member is held in an appropriate orientation regardless of reclining angle of the backrest, wherein the lock means is actuated by means of movement of the inertial body caused when a predetermined acceleration acts on the vehicle body, the vehicle body acceleration sensor being characterized by
the transmission means including a transmission member which can be wrapped around a take-up member provided concentrically and in line with the seat reclining pivot of the backrest, and the sensor case being pivoted in agreement with the amount of the transmission member which is wrapped around the take-up member in association with the reclining action of the backrest.
By means of the foregoing structure of the sensor case, when the transmission member is wrapped around the take-up member, the sensor case is pivoted in agreement with the amount of the transmission member which is wrapped around the take-up member, so that the inertial body support surface is retained in an appropriate orientation. Accordingly, the vehicle body acceleration sensor can properly operate regardless of the reclining angle of the backrest and can sense the acceleration of the vehicle body without fail.
More preferably, when the backrest is reclined forwardly beyond an area which enables an occupant to use the seat, the transmission member is prevented from being wrapped around the take-up member. As a result, the sensor case is prevented from pivoting in synchronization with the backrest and remains stationary. Accordingly, it is possible to eliminate a need for provision of a space for pivotal movement of the sensor case within the retractor corresponding to a range of reclining action of the backrest in which the occupant cannot use the seat, thereby rendering the retractor compact.
More preferably, the end member of the transmission member facing the vehicle body acceleration sensor is wrapped about the a take-up shaft, and the take-up member pivots the sensor case in agreement with the amount of the transmission member that is wrapped around the take-up member, by causing the winding radius of the end member of the transmission member facing the take-up member to match the winding radius of the end member of the transmission member facing the vehicle body acceleration sensor. A take-up surface of the take-up member can be formed into a simple circular arc shape.
The object of the present invention is also achieved by a vehicle body acceleration sensor for use with a seat belt including:
a sensor case which is movably supported by a retractor base mounted on a backrest of a reclining vehicle seat;
a sensor arm which is pivotally mounted on the sensor case or the retractor base so as to move lock means between a first position where the lock means is actuated and a second position where the lock means becomes inoperative, the lock means preventing a take-up shaft, around which a webbing is wound, from rotating in a direction in which the webbing is drawn-out;
an inertial body which moves in relation to an inertial body support surface of the sensor case upon receipt of a velocity change of greater than a predetermined value, thereby moving the sensor arm to the first position; and
transmission means for moving the sensor case in synchronization with reclining action of the backrest according to a reclining angle of the backrest so that the inertial body support member is held in an appropriate orientation regardless of reclining angle of the backrest, wherein the lock means is actuated by means of movement of the inertial body caused when a predetermined acceleration acts on the vehicle body, the vehicle body acceleration sensor being characterized by the transmission means having angle sensing means for sensing the reclining angle of the backrest by detection of relative turning movement between a member which is provided on the backrest and pivots in conjunction with the backrest and a member which is provided in a seat portion; and
a seat pivot shaft placed in line with the seat reclining pivot of the backrest and a pivot shaft of the angle sensing means being provided concentrically and in line with the seat reclining pivot of the backrest, the pivot shafts having irregularities which mesh each other.
By means of the foregoing configuration, the irregularities formed on the seat pivot shaft of the backrest and the irregularities formed on the pivot shaft of the angle sensing means bring the seat reclining pivot of the backrest in alignment with the pivotable axis of the angle sensing means.
Consequently, since the reclining angle of the backrest and the pivoting angle of the angle sensing means match, the transmission means can correctly adjust the orientation of sensing means of the sensor case. Since only requirement is to form irregularities, which mesh each other, on the seat pivot shaft of the backrest and the pivot shaft of the angle sensing means, an increase in manufacturing costs can be prevented.
More preferably, holes used for mounting the angle sensing means are formed so as to be large enough to allow offset of the pitch at which the angle sensing means is attached to the mount section of the seat portion. Therefore, formation of mount holes does not require a high degree of dimensional precision, thereby enabling a reduction in manufacturing costs.
Accordingly, there can be provided a vehicle body acceleration sensor for use with a seat belt which is attached to a retractor positioned in a backrest, is capable of sensing the acceleration of the vehicle body regardless of the reclining angle of the backrest without fail, and enables a reduction in manufacturing costs by employment of a simple structure.